fix: batch priorités — thème, scroll, wizard, agents, slides, charts, packs

Anti-flash dark (color-scheme + applyDocumentTheme), scroll pages publiques,
prompts wizard/slides moins génériques, cron agents rattrapage nextRun null,
slides carnet via notebookId, graphiques à 2 crédits + hint, audit dashboard,
packs Stripe marqués non configurés sans price ID.

memento-note/lib/inline-boot-scripts.ts

@@ -29,6 +29,7 @@ export const THEME_INIT_SCRIPT = `(function () {
     }
     if (wantsDark) root.classList.add('dark');
     else root.classList.remove('dark');
+    try { root.style.colorScheme = wantsDark ? 'dark' : 'light'; } catch (e) {}
     if (theme === 'auto' || theme === 'dark' || theme === 'light') {
       root.removeAttribute('data-theme');
     } else {